Encapsulated structure of light-emitting device, encapsulating process thereof and display device comprising encapsulated structure

ABSTRACT

An encapsulated structure of a light-emitting device, an encapsulating process thereof, and a display device comprising said encapsulated structure. The encapsulated structure of the light-emitting device comprises: a light-emitting device; and a protective layer of a sulfonate salt formed on a top electrode of the light-emitting device, the sulfonate salt having the following structure: 
     
       
         
         
             
             
         
       
         
         
           
             wherein the cation X +  is Li + , Na +  or K + ; and 
             R is a substituent selected from the group consisting of unsubstituted alkyl groups having more than 5 carbon atoms, substituted alkyl groups having more than 5 carbon atoms, and alkoxyl groups having more than 5 carbon atoms.

FIELD OF INVENTION

The invention relates to an encapsulated structure of a light-emitting device, an encapsulating process thereof and a display device comprising the encapsulated structure.

BACKGROUND ARTS

Small molecule organic electroluminescence device (OLED) and Polymer organic electroluminescence device (PLED) have the advantages of active light-emitting, high brightness, full-color display, low driving voltage, low device thickness, flexible display ability, and simpler manufacturing process as compared to the liquid crystal display (LCD) device and plasma display device (PDP), and the like, and have a promising application in large screen flat panel displays and flexible displays.

According to the differences in the organic film materials of the carrier transport layer and the light-emitting layer used in the components, the organic electroluminescence device can be divided into two different classes. One is small molecule-based organic LEDs, briefly OLEDs, which use organic dyes and pigments as the light-emitting materials, wherein a reprehensive example of small molecule light-emitting material is Alq (8-hydroxyquinoline aluminum). The other is polymer-based LEDs, briefly PLED, which use conjugated polymers as the light-emitting materials, wherein a reprehensive example of polymer light-emitting material is PPV (polyphenylene vinylene and derivatives thereof). Organic electroluminescence device is a current type semiconductor light-emitting device based on an organic material. Its structure is typically obtained by forming a light-emitting layer made of an organic light-emitting material with a thickness of some dozens of nanometers on an ITO glass, followed by disposing a layer of low work function metal electrode above the light-emitting layer. When a voltage is applied to the electrode, light radiation occurs in the light-emitting layer.

The organic light-emitting materials in OLED/PLED are very sensitive to water vapor and oxygen gas, and very small amount of water vapor and oxygen gas can damage the organic light-emitting materials and make the light-emitting performance of the device deteriorate. Therefore, it is a very important issue to be solved in the encapsulation of organic electroluminescence device how to reduce the permeation of water vapor and oxygen gas into the encapsulating material of the device and eliminate the water vapor and oxygen gas inside the device. In order to ensure that the device has a service life satisfactory for commercial applications, the permeation rate of the water vapor and oxygen gas into the encapsulated structure and materials of the device should be lower than 10⁻⁶ g/m²/day.

The structure of a bottom emission rigid OLED/PLED device which is conventionally encapsulated is shown in FIG. 1. An organic layer 11 and a metal electrode 12 are vapor deposited onto an ITO glass 9, respectively, and an encapsulating cover 14 attached with a drying slide 13 and a frame sealant 10 is encapsulated onto the ITO glass 9. The organic layer 11 is the light-emitting functional layer which has a structure as shown in FIG. 2, and it may comprise a hole injection layer (HIL) 3, a hole transporting layer (HTL) 4, an organic light-emitting layer (EML) 5, an electron transporting layer (ETL) 6, and an electron injection layer (EIL) 7.

The conventional encapsulating process has such disadvantages as complicated operational procedure, long curing time and high cost, and the like. Moreover, because the drying slide 13 is not transparent, the conventional encapsulating process is only applicable to OLED bottom emission devices but not applicable to top emission devices.

SUMMARY OF INVENTION

An embodiment of the invention provides an encapsulated structure of a light-emitting device comprising,

a light-emitting device; and

a protective layer of sulfonate salt formed on a top electrode of the light-emitting device, the sulfonate salt having the following structure:

wherein the cation X⁺ is Li⁺, Na⁺ or K⁺; and

R is a substituent.

For example, the substituent R is selected from the group consisting of unsubstituted alkyl groups having more than 5 carbon atoms, substituted alkyl groups having more than 5 carbon atoms, and alkoxyl groups having more than 5 carbon atoms.

An embodiment of the invention further provides a display device comprising the encapsulated structure of the light-emitting device as described above.

An embodiment of the invention further provides a process for encapsulating a light-emitting device comprising,

preparing a light-emitting device to be encapsulated, which comprises a substrate; and

forming a protective layer of sulfonate salt on a top electrode of the light-emitting device, the sulfonate salt having the following structure:

wherein the cation X⁺ is Li⁺, Na⁻ or K⁺, and

R is a substituent.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of the components of the encapsulated structure of the organic electroluminescence device in the prior art;

FIG. 2 is a schematic diagram of the structure of the organic layer in the organic electroluminescence device;

FIG. 3 is a flow chart of the process for encapsulating the organic electroluminescence device of the embodiment of the invention;

FIG. 4 is a schematic diagram of the components of the encapsulated structure of the organic electroluminescence device of the embodiment of the invention.

DETAILED DESCRIPTION OF INVENTION

In order to make the technical problem to be solved, the technical solutions and advantages of the invention more clear, detailed descriptions are presented below in conjunction with figures and specific embodiments.

The process for encapsulating an organic electroluminescence device in the prior art has such disadvantages as complicated operational procedure, long curing time, and high cost, and the like, and is only applicable to OLED bottom emission devices but not applicable to top emission devices. In order to solve these issues, an embodiment of the invention provides an encapsulated structure of a light-emitting device, an encapsulating process thereof, and a display device comprising the encapsulated structure. The encapsulated structure allows for encapsulating an OLED top emission device, and the encapsulating process is simple and has the advantages of short curing time, low cost, and good barrier property to oxygen and moisture.

The directions represented by the term “above” or “below” as mentioned in the embodiments of the invention may indicate either direct or indirect contact.

The light-emitting device according to the embodiment of the invention will be described in a form of a top emission organic electroluminescence device. The organic electroluminescence device has a structure typically comprising a substrate, on the surface of which an anode layer, an organic light-emitting layer, and a cathode layer (that is, the cathode or top electrode) are formed successively from bottom to top. The organic electroluminescence device may further comprise one or more of hole injection layers and one or more of hole transporting layers formed successively between the anode layer and the organic light-emitting layer, as well as one or more of electron transporting layers and one or more of electron injection layers formed successively between the organic light-emitting layer and the cathode layer.

An embodiment of the invention provides an encapsulated structure of a light-emitting device comprising,

a light-emitting device; and

a protective layer of a sulfonate salt formed on a top electrode of the light-emitting device, the sulfonate salt having the following structure:

wherein the cation X⁺ is Li⁺, Na⁺ or K⁺; and

R is a substituent.

Furthermore, the substituent R is selected from the group consisting of unsubstituted alkyl groups having more than 5 carbon atoms, substituted alkyl groups having more than 5 carbon atoms, and alkoxyl groups having more than 5 carbon atoms.

Furthermore, the encapsulated structure further comprises:

an encapsulating cover disposed above the protective layer of the sulfonate salt;

the light-emitting device further comprising a substrate,

wherein the encapsulating cover is fixed to the substrate of the light-emitting device with a frame sealant.

Furthermore, the protective layer of the sulfonate salt has a light transmittance of no less than 70%. Furthermore, the protective layer of the sulfonate salt has a thickness of 1 to 100 nm.

The protective layer of the sulfonate salt according to the embodiment of the invention may comprise a single layer or multiple layers. Moreover, the sulfonate salt material in the single layer or in each of multiple layers may be a single is sulfonate salt material or a composite material composed of multiple sulfonate salt materials. As an example, a single layer made of a single material will be described below.

In an embodiment of the invention, a layer of sulfonate salt is formed on the top electrode of the light-emitting device as a device protective layer. The protective layer of the sulfonate salt can form a compact self-assembled film on the metal cathode of the light-emitting device. The anion at one side of the film can undergo a replacement reaction with the surface of the metal cathode to form a more compact protective layer film, and the hydrophobic moiety at the other side can block the invasion of water and oxygen, and protect the device from any damage caused by friction. Therefore, the embodiment of the invention overcomes the disadvantages of the conventional encapsulating process including complicated operational procedure, long curing time, and high cost, and the like, has the advantages of simple operation, short curing time, low cost, and good barrier property to oxygen and moisture, and the like, and applies to encapsulate of an OLED top emission device and an OLED bottom emission device.

An embodiment of the invention also provides a process for encapsulating a light-emitting device comprising,

preparing a light-emitting device to be encapsulated, which comprises a substrate; and

forming a protective layer of a sulfonate salt on a top electrode of the light-emitting device, the sulfonate salt having the following structure:

wherein the cation X⁺ is Li⁺, Na⁺ or K⁺; and

R is a substituent.

As shown in FIG. 3, the encapsulating process of the light-emitting device according to the embodiment of the invention specifically comprises,

Step 301: preparing a light-emitting device comprising a top electrode.

Step 302: forming a protective layer of sulfonate salt on the top electrode of the light-emitting device, the sulfonate salt having the following structure:

wherein the cation X⁺ is Li⁺, Na⁺ or K⁺; and

R is a substituent.

For example, the substituent R is selected from the group consisting of unsubstituted alkyl groups having more than 5 carbon atoms, substituted alkyl groups having more than 5 carbon atoms, and alkoxyl groups having more than 5 carbon atoms.

Solvents useful for dissolving the sulfonate salt may include tetrahydrofuran, benzene, cholorobenzene, or nitrobenzene. For example, the protective layer of the sulfonate salt may be formed by coating a layer of a sulfonate solution on the top electrode of the light-emitting device with spin coating under nitrogen atmosphere. Alternatively, the protective layer of the sulfonate salt may be formed on the top electrode of the light-emitting device by processes such as sputtering, spray coating, and the like.

Alternatively, the light-emitting device may be a top emission light-emitting device, and the protective layer of the sulfonate salt formed on the top electrode of the light-emitting device has a light transmittance of no less than 70%.

Step 303: The light-emitting device with the protective layer of the sulfonate salt formed is transferred into an operation box filled with a protective gas under normal pressure;

For example, the operation box may be a glove box filled with a protective gas under normal pressure.

Step 304: In the operation box, the encapsulating cover is fixed to the substrate of the light-emitting device, and then the light-emitting device is removed from the operation box.

Alternatively, the light-emitting device is a top emission light-emitting device, and the encapsulating cover is transparent.

The process for encapsulating the light-emitting device according to the embodiment of the invention comprises coating a layer of a sulfonate salt on the top electrode of the light-emitting device as the device protective layer, and then pressing a transparent encapsulating cover with a frame sealant attached onto the substrate of the light-emitting device. The protective layer of the sulfonate salt can form a compact self-assembled film on the metal cathode of the organic electroluminescence device. The anion at one side of the film can bind tightly to the metal via electrostatic force, and the hydrophobic moiety at the other side can block the invasion of water and oxygen, and protect the device from any damage caused by friction. The embodiment of the invention overcomes the disadvantages of the conventional encapsulating process including complicated operational procedure, long curing time, and high cost, and the like, has the advantages of simple operation, short curing time, low cost, and good barrier property to oxygen and moisture, and the like, and allows the encapsulation of an OLED top emission device. The process for encapsulating a light-emitting device according to an embodiment of the invention is applicable to both top emission devices and bottom emission devices. For top emission devices, a layer of sulfonate salt with high transmittance in the visible region is formed on the top electrode of the light-emitting device as the device protective layer, and then a transparent encapsulating cover with a frame sealant attached is pressed onto the substrate of the light-emitting device. Therefore, the present disclosure addresses the problem of the conventional encapsulated structures which are only applicable to bottom emission devices.

Below, the encapsulating process and encapsulated structure of the light-emitting device according to the embodiment of the invention are illustrated in details with a top emission organic electroluminescence device as an example.

FIG. 2 is a schematic diagram of an organic electroluminescence device. As shown in FIG. 2, the organic electroluminescence device comprises a substrate 1, on surface of which an anode layer 2, a hole injection layer 3, a hole transporting layer 4, an organic light-emitting layer 5, an electron transporting layer 6, an electron injection layer 7 and a cathode layer 8 are successively stacked from bottom to top.

The substrate 1 may be a glass substrate or a flexible substrate made of a compound such as polyester or polyimide. The anode layer 2 may be made from an inorganic material or an organic conductive polymer, the inorganic material being a metal oxide such as indium tin oxide, zinc oxide, tin zinc oxide, and the like, or a high work function metal such as gold, copper, silver, and the like, and the organic conductive polymer being polythiophene, sodium polyvinyl benzenesulfonate, or polyaniline. The hole injection layer 3 may be formed from copper phthalocyanine (CuPc) or star polyamines such as 2-TNATA (4,4′,4″-tris[2-naphthyl(phenyl)amino]triphenylamine). The hole transporting layer may be formed from a triarylamine material, such as NPB (N,N′-di-(1-naphthyl)-N,N′-diphenyl-1,1-biphenyl-4,4-diamine). The organic light-emitting layer 5 may be formed from a small molecular material, such as a doped fluorescent material or phosphorescent material, for example, MADN (2-methyl-9,10-dinaphthylanthracene), ADN (9,10-dinaphthylanthracene), TBPe (2,5,8,11-tetra-tert-butyl-perylene), Alq₃ (aluminum tris(8-hydroxyquinoline)), Gaq₃ (gallium tris(8-hydroxyquinoline)), Ga (Saph-q) (gallium (III) (salicylidene-o-aminophenol)-(8-hydroxyquinoline)), Rubrene, DCJTB (4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-vinyl)-4H-pyran), Ir(PPy)₃ (iridium tris(2-phenylpyridine)), or CBP (4,4′-N,N′-dicarbazolylbiphenyl). The electron transporting layer 6 may be formed from an organometallic complex, such as Alq₃ (aluminum tris(8-hydroxyquinoline)), gallium tris(8-hydroxyquinoline), gallium (III) (salicylidene-o-aminophenol)-(8-hydroxyquinoline), or from an o-phenanthroline, such as 4,7-diphenyl-1,10-phenanthroline. The electron injection layer 7 may be prepared from an organic electron injection material by way of vapor deposition, and the thickness of the electron injection layer 7 may be from 1 to 10 nm. The cathode layer 8 may be made of a low work function metal, such as lithium (Li), magnesium (Mg), calcium (Ca), strontium (Sr), aluminum (Al), indium (In), and the like, or from an alloy formed from one of them and copper (Cu), gold (Au) or silver (Ag), such as Mg:Ag alloy.

The process for preparing a top emission organic electroluminescence device comprises the steps of:

1) ultrasonically treating the substrate 1 coated with an anode material in a washing agent, rinsing it with a deionized water, ultrasonically de-oiling in an acetone:ethanol mixed solvent (in any ratio), baking under clean conditions until water is completely removed, irradiating with an ultraviolet cleaner for 10-15 minutes, and bombarding the surface of the substrate using low energy cation beam;

2) disposing the substrate 1 with the anode layer 2 in a vacuum chamber at 1×10⁻⁵-9×10⁻³ Pa, vapor depositing on the anode layer a hole injection layer 3 with a thickness of 12-18 nm, followed by a hole transporting layer 4 at a rate of 0.1-0.2 nm/s to produce a vapor deposited film having a thickness of 50-70 nm;

3) vapor depositing an organic light-emitting layer 5 on the hole transporting layer 4 at a rate of 0.1-0.2 nm/s, wherein the material forming the organic light-emitting layer 5 may be selected from the group consisting of TBPe:MADN (MADM comprising 2% by weight; thickness: 30 nm), CBP:Ir(PPy)₃ (Ir(PPy)₃ comprising 7% by weight; thickness: 30 nm), or Alq₃:Rubrene:DCJTB (Rubrene comprising 1.5% by weight, DCJTB comprising 3% by weight; thickness: 60 nm);

4) vapor depositing an electron transporting layer 6 on the organic light-emitting layer 5 at a total rate of 0.1-0.2 nm/s to produce a vapor deposited film having a thickness of 20-40 nm;

5) vapor depositing a layer of Liq on the electron transporting layer 6 as an electron injection layer 7 to produce a vapor deposited film having a thickness of 0.5-3 nm;

6) vapor depositing a cathode layer 8 on the aforesaid electron injection layer 7 at a rate of 2.0-3.0 nm/s to produce a vapor deposited film having a thickness of 10-120 nm.

After the preparation of the top emission organic electroluminescence device is complete, it may be encapsulated using the process for encapsulating an organic electroluminescence device according to the embodiment of the invention. The encapsulating process may comprise the steps of:

A. coating a layer of a sulfonate salt onto the top electrode of the top emission organic electroluminescence device in a vacuum chamber, to produce a protective layer having a transmittance of more than 70% in the visible region and a thickness of 1-100 nm;

B. transferring the top emission organic electroluminescence device from the vacuum chamber to a glove box filled with a protective gas under normal pressure, wherein the content of water and oxygen in the protective gas is on an order of magnitude of ppm;

C. placing an encapsulating cover within the glove box;

D. applying a frame sealant (UV glue or other types of epoxy resins) to edges for encapsulation on the encapsulating cover and the glass substrate of the top emission organic electroluminescence device;

E. matching and jointing the edges for encapsulation on both the glass is substrate of the top emission organic electroluminescence device and the encapsulating cover;

F. delivering the top emission organic electroluminescence device and the encapsulating cover jointed together to the glove box for curing the frame sealant at the edges for encapsulation,

wherein when a UV adhesive is used as the frame sealant, the top emission organic electroluminescence device and the encapsulating cover jointed together are delivered to an ultraviolet exposure device in the glove box to cure the frame sealant at the edges for encapsulation. If a heat curing epoxy resin is used as the frame sealant, the top emission organic electroluminescence device and the encapsulating cover jointed together are delivered to a heat baking device in the glove box to heat-cure the epoxy resin; and

H. removing the encapsulated top emission organic electroluminescence device from the glove box upon the completion of encapsulation.

The structure of the sulfonate salt is shown as follows:

wherein the cation X⁺ is Li⁺, Na⁺ or K⁺; and

R is a substituent.

The substituent R is selected from the group consisting of unsubstituted alkyl groups having more than 5 carbon atoms, substituted alkyl groups having more than 5 carbon atoms, and alkoxyl groups having more than 5 carbon atoms.

For example, the unsubstituted alkyl groups having more than 5 carbon atoms may be selected from the group consisting of n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, and n-eicosane;

the substituted alkyl groups having more than 5 carbon atoms are selected from the group consisting of 2-methylpentane, 3-methylpentane, 2-methylhexane, 3-methylhexane, 2-methylheptane, 3-methylheptane, 2-methyloctane, 3-methyl octane, 2-methylnonane, 3-methylnonane, 2-methyldecane, 3-methyldecane, 2-methylundecane, 3-methylundecane, 2-methyldodecane, 3-methyldodecane, 2-methyltridecane, 3-methyltridecane, 2-methyltetradecane, 3-methyltetradecane, 2-methylpentadecane, 3-methylpentadecane, 2-methylhexadecane, 3-methylhexadecane, 2-methylheptadecane, 3-methylheptadecane, 2-methyloctadecane, 3-methyloctadecane, 2-methylnonadecane, 3-methylnonadecane, 2-methyleicosane, and 3-methyleicosane; and

the alkoxyl groups having more than 5 carbon atoms is OR′, wherein R′ is selected from the group consisting of n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, n-eicosane, 2-methylpentane, 3-methylpentane, 2-methylhexane, 3-methylhexane, 2-methylheptane, 3-methylheptane, 2-methyloctane, 3-methyl octane, 2-methylnonane, 3-methylnonane, 2-methyldecane, 3-methyldecane, 2-methylundecane, 3-methylundecane, 2-methyldodecane, 3-methyldodecane, 2-methyltridecane, 3-methyltridecane, 2-methyltetradecane, 3-methyltetradecane, 2-methylpentadecane, 3-methylpentadecane, 2-methylhexadecane, 3-methylhexadecane, 2-methylheptadecane, 3-methylheptadecane, 2-methyloctadecane, 3-methyloctadecane, 2-methylnonadecane, 3-methylnonadecane, 2-methyleicosane, and 3-methyleicosane.

After the encapsulating process comprising the aforesaid steps A-H, the organic electroluminescence device obtained has an encapsulated structure as shown in FIG. 4, comprising:

an organic electroluminescence device;

a protective layer of a sulfonate salt 15 formed on the top electrode 12 of the organic electroluminescence device;

an encapsulating cover 14 disposed on the organic electroluminescence device coated with the protective layer of the sulfonate salt 15;

wherein the encapsulating cover 14 is jointed with the substrate 1 of the organic electroluminescence device via a frame sealant 10.

The encapsulated structure of the organic electroluminescence device according to the embodiment of the invention is a structure obtained by coating a layer of a sulfonate salt with high transmittance in the visible region on the top electrode of the top emission organic electroluminescence device as the device protective layer, and then pressing a transparent encapsulating cover with a frame sealant attached onto the substrate of the top emission organic electroluminescence device. The protective layer of the sulfonate salt can form a compact self-assembled film on the metal cathode of the organic electroluminescence device. The anion at one side of the film can bind tightly to the metal via electrostatic force, and the hydrophobic moiety at the other side can block the invasion of water and oxygen, and protect the device from any damage caused by friction. Therefore, the embodiment of the invention overcomes the disadvantages of the prior encapsulating process including complicated operational procedure, long curing time, and high cost, and the like, has the advantages of simple operation, short curing time, low cost, and good barrier property to oxygen and moisture, and allows the encapsulation of an OLED top emission device.

The organic electroluminescence device encapsulated according to the embodiment of the invention can be used to manufacture organic transistors, organic integrated circuits, organic solar cells, organic laser, and/or organic sensor.

The encapsulated structure and process for encapsulating the organic electroluminescence device according to the embodiment of the invention are also applicable to a bottom emission organic electroluminescence device. Compared to the process for manufacturing an encapsulated structure of the top emission organic electroluminescence device, the process for manufacturing an encapsulated structure of the bottom emission organic electroluminescence device further comprises a drying slide 13 and a procedure for making the drying slide 13 (see FIGS. 1 and 2).

For the encapsulated structure of the bottom emission organic electroluminescence device, reference can be made to FIGS. 1 and 2. Specifically, the drying slide 13 is positioned above the protective layer of the sulfonate salt (not shown in FIG. 1, which represents the prior art) and below the encapsulating cover 14.

The process for encapsulating a bottom emission organic electroluminescence device comprises manufacturing the bottom emission organic electroluminescence device (see FIGS. 1 and 2). The process is shown as follows:

1) forming an ITO electrode layer on a substrate which may be a glass substrate or a flexible substrate made of a compound such as polyester or polyimide; and

2) vapor depositing a light-emitting functional layer (that is, the organic layer 11) and a metal electrode 12 on the ITO glass 9 under vacuum conditions to form the organic electroluminescence device.

After the preparation of the bottom emission organic electroluminescence device is complete, it can be encapsulated using the process for encapsulating an organic electroluminescence device according to the embodiment of the invention. The encapsulating process may comprise the steps of:

A. coating a layer of a sulfonate salt onto the top electrode of the organic electroluminescence device in a vacuum chamber, to produce a protective layer having a transmittance of more than 70% in the visible region and a thickness of 1-100 nm;

B. transferring the organic electroluminescence device from the vacuum chamber to a glove box filled with a protective gas under normal pressure, wherein the content of water and oxygen in the protective gas is on an order of magnitude of ppm;

C. placing an encapsulating cover 14 to which a drying slide 13 is attached within the glove box;

D. applying a frame sealant (UV adhesive or other types of epoxy resins) to edges for encapsulation on the encapsulating cover and the glass substrate of the top emission organic electroluminescence device;

E. matching and jointing the edges for encapsulation on both the glass substrate of the top emission organic electroluminescence device and the encapsulating cover;

F. delivering the top emission organic electroluminescence device and the encapsulating cover jointed together to the glove box for curing the frame sealant at the edges for encapsulation,

wherein when an UV adhesive is used as the frame sealant, the top emission organic electroluminescence device and the encapsulating cover jointed together are delivered to an ultraviolet exposure device in the glove box to cure the frame sealant at the edges for encapsulation. If a heat curing epoxy resin is used as the frame sealant, the top emission organic electroluminescence device and the encapsulating cover jointed together are delivered to a heat baking device in the glove box to heat-cure the epoxy resin; and

H. removing the encapsulated organic electroluminescence device from the glove box upon the completion of encapsulation.

The organic electroluminescence device encapsulated according to the embodiment of the invention can be used to manufacture organic transistors, organic integrated circuits, organic solar cells, organic laser, and/or organic sensor.

The encapsulating performance of the top emission organic light-emitting devices according to the embodiment of the invention will be illustrated by way of the following examples. However, the invention is not limited to these examples.

Example 1

The structure of the organic electroluminescence device in the example is shown as follows: the anode layer 2 is ITO; the hole injection layer 3 is made of 2-TNANA with a thickness of 15 nm; the hole transporting layer 4 is made of NPB with a thickness of 60 nm; the organic light-emitting layer 5 is made of TBPe:MADN with a thickness of 30 nm, wherein MADN comprises 2% by weight; the electron transporting layer 6 is made of Alq₃ with a thickness of 30 nm; the electron injection layer 7 is made of Liq with a thickness of 2 nm; the cathode layer 8 is made of MgAg with a thickness of 10 nm, wherein the weight ratio of Mg:Ag is 10:1; and the protective layer of the sulfonate salt 15 has a thickness of 50 nm. The structure of the sulfonate salt is shown as follows:

The performance indices of the organic electroluminescence device prior to encapsulation are as follows:

Chrominance Coordinates: (X=0.15, Y=0.20);

Threshold Voltage: 4.2V;

Maximum Brightness: 10020 cd/m² (4V);

Luminous Efficiency: 7.0 cd/A.

The organic electroluminescence device is encapsulated according to the aforesaid encapsulating process. After 30 days, the performance indices of the organic electroluminescence device are as follows:

Chrominance Coordinates: (X=0.15, Y=0.20);

Threshold Voltage: 4.2V;

Maximum Brightness: 9600 cd/m² (4V);

Luminous Efficiency: 6.8 cd/A.

It can be seen that the change in the light-emitting performance of the organic electroluminescence device is minor.

COMPARATIVE EXAMPLE 1

The structure of the organic electroluminescence device in this comparative example is the same as that in EXAMPLE 1, except for absence of protective layer of the sulfonate salt, in which:

the anode layer 2 is ITO; the hole injection layer 3 is made of 2-TNANA with a thickness of 15 nm; the hole transporting layer 4 is made of NPB with a thickness of 60 nm; the organic light-emitting layer 5 is made of TBPe:MADN with a thickness of 30 nm, wherein MADN comprises 2% by weight; the electron transporting layer 6 is made of Alq₃ with a thickness of 30 nm; the electron injection layer 7 is made of Liq with a thickness of 2 nm; the cathode layer 8 is made of MgAg with a thickness of 10 nm, wherein the weight ratio of Mg:Ag is 10:1.

The performance indices of the organic electroluminescence device prior to encapsulation are as follows:

Chrominance Coordinates: (X=0.15, Y=0.20);

Threshold Voltage: 4.2V;

Maximum Brightness: 10020 cd/m² (4V);

Luminous Efficiency: 7.0 cd/A.

The organic electroluminescence device is encapsulated only with a glass cover. After 30 days, the performance indices of the organic electroluminescence device are as follows:

Chrominance Coordinates: (X=0.15, Y=0.20);

Threshold Voltage: 6.8V;

Maximum Brightness: 5200 cd/m² (4V);

Luminous Efficiency: 4.9 cd/A.

It can be seen that the light-emitting performance of the organic electroluminescence device of comparative example 1 deteriorates as compared to the device of EXAMPLE 1.

Example 2

The structure of the organic electroluminescence device in the example is shown as follows: the anode layer 2 is ITO; the hole injection layer 3 is made of 2-TNANA with a thickness of 15 nm; the hole transporting layer 4 is made of NPB with a thickness of 60 nm; the organic light-emitting layer 5 is made of TBPe:MADN with a thickness of 30 nm, wherein MADN comprises 2% by weight; the electron transporting layer 6 is made of Alq₃ with a thickness of 30 nm; the electron injection layer 7 is made of Liq with a thickness of 2 nm; the cathode layer 8 is made of MgAg with a thickness of 10 nm, wherein the weight ratio of Mg:Ag is 10:1; and the protective layer of the sulfonate salt 15 has a thickness of 40 nm. The structure of the sulfonate salt is shown as follows:

The performance indices of the organic electroluminescence device prior to encapsulation are as follows:

Chrominance Coordinates: (X=0.15, Y=0.19);

Threshold Voltage: 4.2V;

Maximum Brightness: 10320 cd/m² (4V);

Luminous Efficiency: 7.1 cd/A.

The organic electroluminescence device is encapsulated according to the aforesaid encapsulating process. After 30 days, the performance indices of the organic electroluminescence device are as follows:

Chrominance Coordinates: (X=0.15, Y=0.19);

Threshold Voltage: 4.2V;

Maximum Brightness: 9800 cd/m² (4V);

Luminous Efficiency: 6.9 cd/A.

It can be seen that the change in the light-emitting performance of the organic electroluminescence device is minor.

Example 3

The structure of the organic electroluminescence device in the example is shown as follows: the anode layer 2 is ITO; the hole injection layer 3 is made of 2-TNANA with a thickness of 15 nm; the hole transporting layer 4 is made of NPB with a thickness of 60 nm; the organic light-emitting layer 5 is made of CBP:Ir(PPy)₃ with a thickness of 30 nm, wherein Ir(PPy)₃ comprises 7% by weight; the electron transporting layer 6 is made of Alq₃ with a thickness of 30 nm; the electron injection layer 7 is made of Liq with a thickness of 2 nm; the cathode layer 8 is made of MgAg with a thickness of 10 nm, wherein the weight ratio of Mg:Ag is 10:1; and the protective layer of the sulfonate salt 15 has a thickness of 30 nm. The structure of the sulfonate salt is shown as follows:

The performance indices of the organic electroluminescence device prior to encapsulation are as follows:

Chrominance Coordinates: (X=0.32, Y=0.63);

Threshold Voltage: 3.0V;

Maximum Brightness: 21500 cd/m² (4V);

Luminous Efficiency: 96 cd/A.

The organic electroluminescence device is encapsulated according to the aforesaid encapsulating process. After 30 days, the performance indices of the organic electroluminescence device are as follows:

Chrominance Coordinates: (X=0.32, Y=0.63);

Threshold Voltage: 3.0V;

Maximum Brightness: 21000 cd/m² (4V);

Luminous Efficiency: 95.6 cd/A.

It can be seen that the change in the light-emitting performance of the organic electroluminescence device is minor.

Example 4

The structure of the organic electroluminescence device in the example is shown as follows: the anode layer 2 is ITO; the hole injection layer 3 is made of 2-TNANA with a thickness of 15 nm; the hole transporting layer 4 is made of NPB with a thickness of 60 nm; the organic light-emitting layer 5 is made of CBP:Ir(PPy)₃ with a thickness of 30 nm, wherein Ir(PPy)₃ comprises 7% by weight; the electron transporting layer 6 is made of Alq₃ with a thickness of 30 nm; the electron injection layer 7 is made of Liq with a thickness of 2 nm; the cathode layer 8 is made of MgAg with a thickness of 10 nm, wherein the weight ratio of Mg:Ag is 10:1; and the protective layer of the sulfonate salt 15 has a thickness of 25 nm. The structure of the sulfonate salt is shown as follows:

The performance indices of the organic electroluminescence device prior to encapsulation are as follows:

Chrominance Coordinates: (X=0.32, Y=0.63);

Threshold Voltage: 2.8V;

Maximum Brightness: 25500 cd/m² (6V);

Luminous Efficiency: 85 cd/A.

The organic electroluminescence device is encapsulated according to the aforesaid encapsulating process. After 30 days, the performance indices of the organic electroluminescence device are as follows:

Chrominance Coordinates: (X=0.32, Y=0.63);

Threshold Voltage: 3.0V;

Maximum Brightness: 25500 cd/m² (6V);

Luminous Efficiency: 82 cd/A.

It can be seen that the change in the light-emitting performance of the organic electroluminescence device is minor.

Example 5

The structure of the organic electroluminescence device in the example is shown as follows: the anode layer 2 is ITO; the hole injection layer 3 is made of 2-TNANA with a thickness of 15 nm; the hole transporting layer 4 is made of NPB with a thickness of 60 nm; the organic light-emitting layer 5 is made of CBP:Ir(PPy)₃ with a thickness of 30 nm, wherein Ir(PPy)₃ comprises 7% by weight; the electron transporting layer 6 is made of Alq₃ with a thickness of 30 nm; the electron injection layer 7 is made of Liq with a thickness of 2 nm; the cathode layer 8 is made of MgAg with a thickness of 10 nm, wherein the weight ratio of Mg:Ag is 10:1; and the protective layer of the sulfonate salt 15 has a thickness of 45 nm. The structure of the sulfonate salt is shown as follows:

The performance indices of the organic electroluminescence device prior to encapsulation are as follows:

Chrominance Coordinates: (X=0.32, Y=0.63);

Threshold Voltage: 3.5V;

Maximum Brightness: 18500 cd/m² (6V);

Luminous Efficiency: 90 cd/A.

The organic electroluminescence device is encapsulated according to the aforesaid encapsulating process. After 30 days, the performance indices of the organic electroluminescence device are as follows:

Chrominance Coordinates: (X=0.32, Y=0.63);

Threshold Voltage: 3.7V;

Maximum Brightness: 17000 cd/m² (6V);

Luminous Efficiency: 88 cd/A.

It can be seen that the change in the light-emitting performance of the organic electroluminescence device is minor.

Example 6

The structure of the organic electroluminescence device in the example is shown as follows: the anode layer 2 is ITO; the hole injection layer 3 is made of 2-TNANA with a thickness of 15 nm; the hole transporting layer 4 is made of NPB with a thickness of 60 nm; the organic light-emitting layer 5 is made of CBP:Ir(PPy)₃ with a thickness of 30 nm, wherein Ir(PPy)₃ comprises 7% by weight; the electron transporting layer 6 is made of Alq₃ with a thickness of 30 nm; the electron injection layer 7 is made of Liq with a thickness of 2 nm; the cathode layer 8 is made of MgAg with a thickness of 10 nm, wherein the weight ratio of Mg:Ag is 10:1; and the protective layer of the sulfonate salt 15 has a thickness of 35 nm. The structure of the sulfonate salt is shown as follows:

The performance indices of the organic electroluminescence device prior to encapsulation are as follows:

Chrominance Coordinates: (X=0.33, Y=0.63);

Threshold Voltage: 3.6V;

Maximum Brightness: 26500 cd/m² (6V);

Luminous Efficiency: 92 cd/A.

The organic electroluminescence device is encapsulated according to the aforesaid encapsulating process. After 30 days, the performance indices of the organic electroluminescence device are as follows:

Chrominance Coordinates: (X=0.33, Y=0.63);

Threshold Voltage: 3.7V;

Maximum Brightness: 24000 cd/m² (6V);

Luminous Efficiency: 87 cd/A.

It can be seen that the change in the light-emitting performance of the organic electroluminescence device is minor

Example 7

The structure of the organic electroluminescence device in the example is shown as follows: the anode layer 2 is ITO; the hole injection layer 3 is made of 2-TNANA with a thickness of 15 nm; the hole transporting layer 4 is made of NPB with a thickness of 60 nm; the organic light-emitting layer 5 is made of Alg₃:Rubrene:DCJTB with a thickness of 60 nm, wherein Rubrene comprises 1.5% by weight and DCJTB comprises 3% by weight; the electron transporting layer 6 is made of Alq₃ with a thickness of 30 nm; the electron injection layer 7 is made of Liq with a thickness of 2 nm; the cathode layer 8 is made of MgAg with a thickness of 10 nm, wherein the weight ratio of Mg:Ag is 10:1; and the protective layer of the sulfonate salt 15 has a thickness of 20 nm. The structure of the sulfonate salt is shown as follows:

The performance indices of the organic electroluminescence device prior to encapsulation are as follows:

Chrominance Coordinates: (X=0.64, Y=0.34);

Threshold Voltage: 4.0V;

Maximum Brightness: 11000 cd/m² (5V);

Luminous Efficiency: 8 cd/A.

The organic electroluminescence device is encapsulated according to the aforesaid encapsulating process. After 30 days, the performance indices of the organic electroluminescence device are as follows:

Chrominance Coordinates: (X=0.64, Y=0.34);

Threshold Voltage: 4.0V,

Maximum Brightness: 10500 cd/m² (5V);

Luminous Efficiency: 7.8 cd/A.

It can be seen that the change in the light-emitting performance of the organic electroluminescence device is minor.

Example 8

The structure of the organic electroluminescence device in the example is shown as follows: the anode layer 2 is ITO; the hole injection layer 3 is made of 2-TNANA with a thickness of 15 nm; the hole transporting layer 4 is made of NPB with a thickness of 60 nm; the organic light-emitting layer 5 is made of Alq₃:Rubrene:DCJTB with a thickness of 60 nm, wherein Rubrene comprises 1.5% by weight and DCJTB comprises 3% by weight; the electron transporting layer 6 is made of Alq₃ with a thickness of 30 nm; the electron injection layer 7 is made of Liq with a thickness of 2 nm; the cathode layer 8 is made of MgAg with a thickness of 10 nm, wherein the weight ratio of Mg:Ag is 10:1; and the protective layer of the sulfonate salt 15 has a thickness of 55 nm. The structure of the sulfonate salt is shown as follows:

The performance indices of the organic electroluminescence device prior to encapsulation are as follows:

Chrominance Coordinates: (X=0.64, Y=0.34);

Threshold Voltage: 3.6V;

Maximum Brightness: 15000 cd/m² (5V);

Luminous Efficiency: 9 cd/A.

The organic electroluminescence device is encapsulated according to the aforesaid encapsulating process. After 30 days, the performance indices of the organic electroluminescence device are as follows:

Chrominance Coordinates: (X=0.64, Y=0.34);

Threshold Voltage: 4.0V;

Maximum Brightness: 13500 cd/m² (5V);

Luminous Efficiency: 7.8 cd/A.

It can be seen that the change in the light-emitting performance of the organic electroluminescence device is minor.

Example 9

The structure of the organic electroluminescence device in the example is shown as follows: the anode layer 2 is ITO; the hole injection layer 3 is made of 2-TNANA with a thickness of 15 nm; the hole transporting layer 4 is made of NPB with a thickness of 60 nm; the organic light-emitting layer 5 is made of Alq₃:Rubrene:DCJTB with a thickness of 60 nm, wherein Rubrene comprises 1.5% by weight and DCJTB comprises 3% by weight; the electron transporting layer 6 is made of Alq₃ with a thickness of 30 nm; the electron injection layer 7 is made of Liq with a thickness of 2 nm; the cathode layer 8 is made of MgAg with a thickness of 10 nm, wherein the weight ratio of Mg:Ag is 10:1; and the protective layer of the sulfonate salt 15 has a thickness of 70 nm. The structure of the sulfonate salt is shown as follows:

The performance indices of the organic electroluminescence device prior to encapsulation are as follows:

Chrominance Coordinates: (X=0.64, Y=0.34);

Threshold Voltage: 3.2V;

Maximum Brightness: 17000 cd/m² (5V);

Luminous Efficiency: 10 cd/A.

The organic electroluminescence device is encapsulated according to the aforesaid encapsulating process. After 30 days, the performance indices of the organic electroluminescence device are as follows:

Chrominance Coordinates: (X=0.64, Y=0.34);

Threshold Voltage: 3.5V;

Maximum Brightness: 15500 cd/m² (5V);

Luminous Efficiency: 8.8 cd/A.

It can be seen that the change in the light-emitting performance of the organic electroluminescence device is minor.

It should appreciate that in the aforesaid examples, sodium sulfonate is taken as examples, and because Li⁺, Na⁺ and K⁺ are all alkali metal ions and share close chemical properties, a substituent suitable for sodium sulfonate structure is also suitable for the sulfonate salt structure with other alkali metal ions.

From the aforesaid example, it can be seen that after encapsulating the organic electroluminescence device through the process for encapsulating an organic electroluminescence device according to the invention, the sulfonate salt can undergo a replacement reaction with the surface of the metal cathode of the light-emitting device to form a more compact protective layer film, and the hydrophobic moiety at the other side can block the invasion of water and oxygen, and protect the device from any damage caused by friction, ensuring the excellent performance of the organic electroluminescence device. Therefore, the embodiment of the invention overcomes the disadvantages of the conventional encapsulating process including complicated operational procedure, long curing time, and high cost, and the like, and has the advantages of simple operation, short curing time, low cost, and good barrier property to oxygen and moisture.

In the examples of various methods according to the invention, the to numberings for the steps are not intended to limit the order of performing various steps. To a person of ordinary skill in the art, modification to the order of the steps, without resorting to inventive work, will fall into the scope of the invention.

The preferable embodiments of the invention are described above. It should understand that a person of ordinary skill in the art can make improvements and modifications without departing from the principle of the invention, and these improvements and modifications should be considered within the scope of the invention. 

The invention claimed is:
 1. An encapsulated structure of a light-emitting device, comprising, a light-emitting device; a protective layer of a sulfonate salt formed on a top electrode of the light-emitting device, the sulfonate salt having the following structure:

wherein the cation X⁺ is Li⁺, Na⁺ or K⁺; and R is a substituent, and wherein, the substituent R is selected from the group consisting of unsubstituted alkyl groups having more than 5 carbon atoms, substituted alkyl groups having more than 5 carbon atoms, and alkoxyl groups having more than 5 carbon atoms.
 2. The encapsulated structure according to claim 1, wherein, the unsubstituted alkyl groups having more than 5 carbon atoms are selected from the group consisting of n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, and n-eicosane; the substituted alkyl groups having more than 5 carbon atoms are selected from the group consisting of 2-methylpentane, 3-methylpentane, 2-methylhexane, 3-methylhexane, 2-methylheptane, 3-methylheptane, 2-methyloctane, 3-methyloctane, 2-methylnonane, 3-methylnonane, 2-methyldecane, 3-methyldecane, 2-methylundecane, 3-methylundecane, 2-methyldodecane, 3-methyldodecane, 2-methyltridecane, 3-methyltridecane, 2-methyltetradecane, 3methyltetradecane, 2-methylpentadecane, 3-methylpentadecane, 2-methylhexadecane 3-methylhexadecane, 2-methylheptadecane, 3-methylheptadecane, 2-methyloctadecane, 3-methyloctadecane, 2-methylnonadecane, 3-methylnonadecane, 2-methyleicosane, and 3-methyleicosane; and the alkoxyl groups having more than 5 carbon atoms is OR′, wherein R′ is selected from the group consisting of n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, n-eicosane, 2-methylpentane, 3-methylpentane, 2-methylhexane, 3-methylhexane, 2-methylheptane, 3-methyiheptane, 2methyloctane, 3-methyloctane, 2-methylnonane, 3-methylnonane, 2-methyldecane, 3-methyldecane, 2-methylundecane, 3-methylundecane, 2-methyldodecane, 3-methyldodecane, 2-methyltridecane, 3-methyltridecane, 2-methyltetradecane, 3-methyltetradecane, 2-methylpentadecane, 3-methylpentadecane, 2-methylhexadecane, 3-methylhexadecane, 2-methylheptadecane, 3-methylheptadecane, 2-methyloctadecane, 3-methyloctadecane, 2-methylnonadecane, 3-methylnonadecane, 2-methyleicosane, and 3-methyleicosane.
 3. The encapsulated structure according to claim 1 further comprising, an encapsulating cover disposed above the protective layer of the sulfonate salt; the light-emitting device further comprises a substrate, wherein the encapsulating cover is fixed to the substrate of the light-emitting device with a frame sealant.
 4. The encapsulated structure according to claim 1, wherein the protective layer of the sulfonate salt has a light transmittance of no less than 70%.
 5. The encapsulated structure according to claim 1, wherein the protective layer of the sulfonate salt has a thickness of 1 to 100 nm.
 6. A display device comprising the encapsulated structure of the light-emitting device according to claim
 1. 7. A process for encapsulating a light-emitting device comprising, preparing a light-emitting device to be encapsulated, which comprises a substrate; and forming a protective layer of a suifonate salt on a top electrode of the light-emitting device, the sulfonate salt having the following structure:

wherein the cation X⁺ is Li⁺, Na⁺ or K⁺; and R is a substituent, and wherein, the substituent R is selected from the group consisting of unsubstituted alkyl groups having more than 5 carbon atoms, substituted alkyl groups having more than 5 carbon atoms, and alkoxyl groups having more than 5 carbon atoms.
 8. The process for encapsulating a light-emitting device according to claim 7 further comprising: disposing an encapsulating cover above the protective layer of the sulfonate salt; and fixing the encapsulating cover to the substrate of the light-emitting device.
 9. The process for encapsulating a light-emitting device according to claim 8, wherein the fixing the encapsulating cover to the substrate of the light-emitting device comprises, applying a frame sealant to edges for encapsulation on the encapsulating cover and the substrate of the light-emitting device; and curing the frame sealant at the edges. 